If the post does not get removed you do NOT know that you have fully achieved ownership. The simple fact that that clause exists means you do not have full ownership.
Hosting on a pi might not make much difference as most ISP's have similar clauses in their EUP's.
The only way to come close to "full ownership" I can think of would be by either owning the entire stack to the reader or maybe some encrypted p2p system. Does anyone have any practical suggestions?